NL8000366A - PROCESS FOR THE PREPARATION OF 4A-ZEOLITES WITH A LARGE CRYSTALLINITY AND A FINE GRIT SIZE DISTRIBUTION. - Google Patents

Description

Process for the preparation of 1 + A zeolites with a high crystallinity and a fine grain size distribution.

The invention relates to a process for the preparation of 1 + A zeolites with a high crystallinity and a fine grain size distribution, which are particularly suitable for the preparation of cleaning agent mixtures.

Belgian patent 860,757 describes a process for the preparation of zeolites of this type in which a warm (70 ° C) solution of a certain sodium silicate is treated with a warm (70 ° C) solution of sodium aluminate containing an excess of NaOH contains add; the silicate solution is prepared by mixing together with stirring an aqueous water glass solution in which the molar ratio SiO 2: Na 2 O = 3, k6, with an aqueous solution of NaOH so that the molar ratio decreases to 1.65. On the other hand, in French Patent Specification 2,096,360 taught to pour the warm silicate solution into the warm aluminate solution previously introduced into a reactor and another Belgian patent, 862.7i + 0 describes a process in which both solutions are both mixed at low temperature.

According to these patents, particles with a high crystallinity and a fine grain size distribution can be obtained; however, the statistical particle size distribution is not entirely satisfactory. It is known that for use in cleaning agent mixtures the particles must all have a particle size that is completely between 1 and 10 µm. Particles with a particle size of more than 10 µm give a slow exchange with calcium ions and in particular with magnesium ions and leave residues on textile materials and clog drain pipes; particles with a particle size of less than 1 / m penetrate deeply into the 0 3 βδ 2 \ meshes or openings of the textile materials which are washed with detergents containing such mixtures, gradually making the textile materials concerned increasingly matt, while remaining much have a long settling time in order to be able to separate 5 in the ecological vessels for the treatment of wastewater by galvanizing. Experience has shown that the best results in the form of a good cleaning power without ecological problems are only achieved if the granulometric modulation index is sufficiently high and the fraction of particles with a large grain size is negligible; by the "granulometric modulation index" (Cu) is meant the weight percentage of particles with a particle size of 3 to 8 / au, when the granulometric analysis is carried out with a "Coulter counter", as described in Belgian patent 860,757 and by "the fraction of coarse particles" (ol) is meant the weight percentage of particles with a particle size of more than 10 µm (found by analysis with a Coulter counter). Another drawback of the method is the complexity and the slow reaction speed.

The object of the invention is therefore to provide a simpler, faster and more flexible method which leads to a product with the same or even better properties, in particular a product that has a greater softening effect on water whose hardness is caused by magnesium ions. .

According to the invention there is provided a process for the preparation of 4A zeolites with a high crystallinity and a fine grain size distribution by adding, in a first step, an aqueous sodium silicate solution to an aqueous sodium aluminate solution containing an excess of NaOH and is Heated at a temperature of 50 to 100 ° C, and by crystallizing, in a second stage, at a temperature of 70 to 105 ° C, which method is characterized in that the temperature of the silicate solution is at least 20 ° C lower then the temperature of the aluminate solution, the molar ratios SiOgJHgO and SiOgiNagO in the silicate solution, respectively. are between 0.030 and 0.150 and between 1.95 and 2.30 and the weight ratio ('X') between the reaction mother 80 0 0 3 66

# -V

3 liquid and the zeolite thus formed, being the product with 22% w / w crystal water, is between 6.5 and 20 and preferably between 8 and 15, the ratio (T) being represented by the equation: 5 g Na 2 O + g Al2 O3 + gSiO2 + g HgO - g SiO2 / 0.3288 r = - g SiO2 / 0.3288 in which the symbols g Na2 O, g AlgO2, etc., represent the weights of the reagents fed in grams.

With this method it is possible to obtain kA zeolites with a high crystallinity and with a fine grain size distribution, with a granulometric modulation index (u?) Equal to or greater than 85 and with a fraction of coarse particles (« () which is equal to or less than 1 (and may even be 0).

The products obtained with the method according to the invention have a very high ion exchange capacity also for water which is hard due to the presence of magnesium ions; exchange with magnesium ions is possible in practice to an extent equivalent (equivalent to) 1 * 5 mg CaO / g (or even in some 20 cases 50 mg CaO / g), measured by the method described below.

The invention is particularly surprising when it is taken into account that the water glass in which the molar ratio SiO 2: Na 2 O = about 3.1 * 6 (a product used in most other preparation methods) is prepared by a mixture of silica sand and sodium carbonate in a melting furnace (which is associated with a certain loss of energy), while the sodium disilicate (NagSigOcj) and the other silicates of the invention can be obtained directly in a much less complicated way by dissolving the silicon dioxide in a solution of NaOH hot 30. The rate at which the zeolite is formed is very high and the process exhibits a high degree of flexibility in reaction conditions such as temperature, reaction time, flexibility which generally does not occur in processes using too high SiO 2: Na 2 O 35 relationships; zeolites according to the invention were tested in an 80 0 0 3 66 1 * number of mixtures as described in the Belgian patent 860,757, in the Italian patent 1,009.¼½ and in the US patent 1 * .0Ö3.793, always obtaining excellent results .

The method according to the invention can be carried out in various ways. For example, it is convenient to add the silicate solution within a time period of up to 15 minutes and the temperature of the mixture in the first stage of the synthesis is suitably kept equal to that of the aluminate solution, the latter preferably having a temperature between 70 and 75 ° C. In addition, it is advantageous to divide the second stage into three sub-stages, the first sub-stage of which is characterized by using a temperature equal to the temperature in the first stage, the second-stage is characterized by allowing the temperature to rise from 70 up to 105 ° C and the third bottom stage is characterized in that the temperature is kept constant between 95 and 105 ° C. The duration of the sub-stages is between 30 and 60 minutes (preferably between 1 * 0 and 50 minutes) for the first stage, between 10 and 80 minutes (preferably between 20 * 15 and 1 * 0 minutes) for the second stage and between 10 and 90 minutes (preferably between 15 and 60 minutes) for the third stage.

To make the reaction mixture homogeneous, it is only necessary to stir gently; the reaction suspension may be suitably filtered or centrifuged to separate the fine crystals and the mother liquor, after the crystals have been separated, may be discharged or recycled to prepare the aluminate solution.

Another variant consists in that a new aluminate charge is separately achieved while the reactor is operating.

The process can be carried out batchwise or continuously.

Fig. 1 schematically shows a possible batchwise implementation of the method according to the invention.

Fig. 2 shows a variant of FIG. 1 and FIG.

3 and 1 * represent graphs of the most significant results.

According to Fig. 1 NaOH is introduced successively into a reactor (A) via line 1, then Αΐ (ΌΈ.) ^ (Through line 2) 80 0 0 3 66 * * - * 5 and then deionized water. The formed aluminate solution is then reacted with a solution of disilicate (fed through line U) and the reaction mixture discharged through line (5) is then centrifuged in (B) of the mother liquor discharged through line (6) to the collect box (C). If the sodium hydroxide-rich mother liquor is recycled to partially replace the deionized water and the NaOH, this mother liquor is recycled through line (7) · Ce centrifuged fine crystals are washed with deionized water (line 8) and then by conduit (9) transferred to a tray (D) where the cake is resuspended with more deionized water (conduit 10); the formed suspension (11) is then placed in a spray dryer (E) and the formed dry zeolite (12) is taken to a storage (F). In case dryers of a different type are used, the cake (9) is fed directly to the drying stage (E) and then to the storage (F).

The meaning of the other figures is evident from the examples illustrating the invention.

Example I

In a stainless steel reactor / "(reactor A) in fig. 1. / with a capacity of 1200 l equipped with a thermostatically controlled heating system and with a reflux condenser. 1 and a stirrer making 120 mm. - 239 kg of an aqueous NaOH solution with a concentration of 3 ^ 3 by weight Na 2 O, as well as 7 kg of hydrated alumina, content 60 wt.% AlgO 2 and 5 ^ 5 µg deionized water. kept at 100 ° C until a clear sodium aluminate solution was obtained with a molar ratio NagQiAlgQ ^ of 3.35 and with a Na 2 O content of 9> 2 wt.%, the solution was cooled to 70 ° C and in 13 min. with stirring, added 209 kg of a second aqueous solution, temperature 7 ° C, containing 8.7 wt.% Na2Q and 18.1 wt.% SiOg.

Na 2 O was 2.2, a value close to that for the stoichiometry composition of the disilicate (NagSigO 2); the amount added was such that the weight ratios of 80 0 0 3 86 6 became the components in the reaction mixture: Na 2 AlgO 2 = 2.1 + 9, Na 2 O: SiO 2 = 2.60, H 2 O: SiO 2 = 23.91+.

Then the mixture was fed to the second stage, i.e. the crystallization of the aluminum silicate. First, the mixture was kept at 70 ° C for 1 + 5 min in a first sub-stage, after which the temperature was slowly increased from 70 to 100 ° C over 15 min. Finally, the mixture was heated to 100 ° C under atmospheric pressure for 90 min with gentle stirring. The solid was separated from the mother liquor by a basket centrifuge rotating on a vertical axis (centrifuge (B) in Figure 1) and the resulting cake was then washed with deionized water until the washing liquid had a pH of 11.3. An aqueous suspension containing 5l + lig zeolite per 100l suspension was obtained and dried in a spray dryer (device (E) in Fig. 1), yielding a crystalline 1 + A zeolite having the following composition: 1 .01 NagO.AlgOg. 1.98 SiO2.1 +, 51 HgO. Subsequently, the exchange capacity of the zeolite with calcium was determined in the following manner.

An aqueous 0.005 molar solution of calcium-20 nitrate tetrahydrate, i.e. a solution with a hardness of 50 ° French, was prepared by dissolving 1.181 g of CaiNO ^ 1 + HgO in deionized water and then supplementing the solution to a volume of 1 l. To this solution was added 1 g of hydrated zeolite and the suspension formed was stirred vigorously with a magnetic stirrer at a temperature of 22 + 2 ° C for 15 min. 100 ml of this solution were then filtered on a porous plate (porosity = 1 +) and the Ca ++ concentration was determined by titration with a 0.01N solution of the disodium salt of ethylenediamine tetraacetic acid (EDTA); the ion exchange capacity of the hydrated zeolite was first calculated in mg CaO per g zeolite, using the formula: PS (Ca) (50-cm3 EDTA) x 5.6, where "cm3EDTA" means the number of cm3 of the 0 .01N EDTA solution consumed at the titration and which means hydrated zeolite a product which is in equilibrium with air with an 80 0 0 3 66 # · * 7

moisture content of not less than 50% at room temperature (between 15 and 30 ° C). The "hydrated" zeolite was obtained by heating the filtered and washed product in an oven at 105 ° C for 5h. The dried material was then triturated in a mortar and then exposed to air with a relative humidity of not less than 50% at a temperature between 15 and 30 ° C for not less than 3h. Then, by determining the moisture content of the hydrated zeolite by calcining at 800 ° C for 1 h, the exchange capacity of 10 Per S vessel-free product was determined. The tables shown in Tables A to E

stated values apply to anhydrous zeolite. The magnesium exchange capacity was similarly determined using a 0.005 molar solution of MgSO4 containing 1,232g MgSO4THgO per liter. The exchanging power for magnesium was first calculated in mg CaO per g hydrated zeolite using the formula PS (Mg) = 50 cm ^ EDTA) x 5> 6, after which the exchanging power of the anhydrous product (which is in the Table A - E is reported) calculated in exactly the same manner as mentioned above for calcium.

To determine the exchange rate, the experiments were repeated with calcium and magnesium, reducing the time the zeolite was stirred with the solution from 15 to 2 minutes. The rate of the exchange reaction is an important given because the sequestering action of the zeolite is to be performed in a conventional washing machine in a short time of several minutes; the high exchanging capacity for magnesium ion-containing water, listed in Table A, represents an important step forward compared to the results obtained so far. The granulometric analysis (determined with a Coulter counter) gave the results listed in Table A which are also reported in Figure 3 and I. An X-ray diffraction analysis determined that the zeolite was a perfectly crystalline A zeolite. Below are shown the interfacial distances with the corresponding indices and the intensities of the diffraction peaks.

80 0 0 3 66 8 hkl d (X) I / Io hkl d (8) I / Io 100 12.29 100 221.3 fc, 11 36.5 110 8.71 69.5 311 3.71¾ 53 5 111 7.11 3¾.5 320 3.1 * 17 16.5 210 5.51 25.5 321 3,293 1 * 6.5 211 5.03 2 UlO 2,988 55.5 220 U, 36 6 10

Example II

A reaction system as shown in Fig. 2 was used. In a reactor (C) equal to the reactor (A) and corresponding to the reactor (A) of Example I, 898 kg of a recycled were charged. mother liquor (6) consisting of a solution containing 7.99 wt.% NagO and 0.85 wt. To this solution were then added with stirring (via lines 1 and 2) 30 kg of a 3.3 wt.% Solution of NagO and 55 kg of hydrated alumina with a 60.87 wt. the solution was then cooled to 70 ° C and transferred to reactor A. To reactor A were also added, in 10 min, with stirring, 155 kg of an aqueous silicate solution at a temperature of 10 ° C, which was 11.7¾ wt. $ NagO and 2 ^ 82 wt% SiOg (molar ratio SiOg: Nag0 = 2.18). The weight ratio between the various components of the mixture were:

Na2O: AlgO3 * 2Mi NagO: SiOg = 2.61; Hg0: Si0g = 2¾.36.

Crystallization then took place and was centrifuged and dried as described in Example I to obtain analogous results (see Table E).

Example III

Into the reactor described in Example 1 were charged 307 kg of solution containing 29 wt.% NagO, 67.2 kg of hydrated alumina with an AlGO content of 60.38% and 591.5 kg of deionized water. The temperature was held at 100 ° C for 1h until a clear solution was formed in which the molar ratio of NagO: AlgO ^ 80 0 0 3 66 9 was 3.61 and the weight percentage was 10 wt% 22 wt. The reaction mass was then cooled to 70 ° C and charged to the reactor with stirring in 15 min. 13 * +, 3 kg of a water glass solution, temperature 8 ° C, containing 8.2 * +% by weight Na 2 O and 28 .69 wt.% SiO2 and 5 wherein the mole ratio SiO2: Na2O was 3.6; the proportions between the various components of the mixture are listed in Table A. Thereafter, crystallization took place and centrifuged and dried as described in Example I, yielding poor results which are also listed in Table A.

This proves that it is recommended to avoid too high SiO2 / Na2O ratios in the silicate solution. In the X-ray diffraction spectrum, the peaks had a mean intensity 10 $ lower than the values found in Example 1 and .....

which are determined that other crystalline compounds were present.

Example IV

Into the same reactor as described in Example 1, 2 ^ 3.3 kg of a solution containing 35.3 wt.% Na2 O, 67.2 kg of hydrated alumina with an AlgO2 content of 60.38 wt. + 6.2 kg of deionized water. The reaction mixture was held at 100 ° C for 1h until the clear solution was formed whose molar ratio was 1120: Al2O ^ 3.1 + 8 and the weight percent Na2O was 3.98 wt%. The reaction mixture was cooled to 70 ° C and in 15 minutes, 11 + -3.3 kg of a silicate solution, temperature 8 ° C, which was 9.93 wt.

NagO and 26.90 wt% SiOg and wherein the SiO 2: Na 2 O molar ratio was 2.8. The weight ratios of the components of the reaction mixture were as reported in Table A. Then crystallization, centrifugation and drying were carried out as described in Example 1. The results are reported in Table A. These results, which are based on a ratio SiOgiNa = 2 8, ie slightly lower than the ratio in example III, were slightly better (compared to example III), but were still far from the excellent results from example I,

35 Example V

8a2sia ° 5 80 0 0 3 66 10

Into the reactor of Example 1 were charged 227.6 kg of a solution containing 35.05 wt.% Na 2 O, 67.2 kg of hydrated alumina with an Al 2 O 2 content of 60.38 wt. 637.9 kg of deionized water. This mixture was kept at 100 ° C for 1 h until the clear solution was formed, in which the molar ratio Na 2 AlgO 2 3.23 and in which the NagO content was 8.55 wt%. Then, the reaction mass was cooled to 70 ° C and 167.8 kg of a silicate solution, temperature 8 ° C, containing 31 + 9 wt.% Sodium disilicate (Na 2 ^ 3) was added over 15 minutes with stirring. the molar ratio

SiOgiNagO was 2. The weight ratios between the different components of the reaction mixture are shown in Table A.

Crystallization, centrifugation and drying were then carried out, just as in Example I, with which results listed in Table A were obtained.

Example VI

218 kg of a solution containing 35.05% by weight of Na 2 Q, 67.2 kg of hydrated alumina, Al content of 60.38% by weight and 636.6 kg of deionized water were charged to the reactor of Example 1. This reaction mixture was held at 100 ° C for 1h until a clear solution was formed in which the molar ratio Na 2 O: Al 2 O 2 3.11 and in which the 20 O content was 8.31% by weight. The reaction mixture was cooled to 70 ° C and 177.5 kg of a silicate solution, temperature 8 ° C, containing 13.20% by weight Na 2 O and 21.71 was added to the reactor over 15 minutes with stirring. % SiOg and in which the SiO 2: Na 2 O mol ratio was 1.7. The weight ratios of the various components of the reaction mixture are shown in Table 3. Then crystallization, centrifugation and drying were carried out as described in Example I to obtain the results listed in Table B.

Example VII

In this case, Example I was repeated except that the overall composition of the reaction mixture (see Table B) was left unchanged but the composition of the starting solutions was changed so that in the silicate solution the ratio SiOgiNagO was 2.5. The results are reported 80 0 0 3 86 * »11 in Table B.

Examples VIII and IX

Example I repeated several times only changing the time for adding silicate to the aluminate.

In Example VIII, the time was set to 1 * 5 min. Instead of 13 min. In Example I, and in Example IX, the time was set to 5 min. The results are shown in Table B.

Example X.

Into the reactor of Example 1, 250 kg of a 35 wt.% Solution of Na 2 O, 71 kg of 5 hydrated alumina with an AlgO 2 content of 63.2 wt.% And 633 kg of deionized water were charged. The reaction mixture was heated to 100 ° C until the hydrated alumina dissolved. This solution was then cooled to 70 ° C and 2 ^ 6 kg of an aqueous solution at a temperature of 65 ° C, containing 17.1 wt / S SiO 2 and 8.83 wt, were added with stirring in 15 min. . $

Ha20 contained, mole ratio SiOgjNa ^ O = 2. The ratios between the various components of the reaction mixture are shown in Table C, which also lists the results obtained after crystallization, centrifugation and drying in the manner described in Example 1. The large fraction coarse particles) of 2 wt. particles with a particle size of more than 10 µm, is an indication of a bad product (and in every respect less valuable product than the product of Example 1) and shows that it is necessary keep the temperature of the silicate solution below the reaction temperature.

Example XI

Example X was repeated changing only the temperature of the silicate solution from 65 ° C to 50 ° C. Table C, which shows the data and results, shows that there was a clear improvement due to the temperature decrease. The influence of the temperature speaks even more clearly when one compares the results from example X (temperature 65 ° C) with the excellent results from example I (temperature 7 ° C).

Example XII

Example X was repeated with the following variations: 80 0 0 3 66 12 a) temperature of the silicate solution was lowered to 23 ° C; b) after the addition of silicate to the aluminate (first stage), the crystallization (second stage) was carried out while the temperature was kept at 70 ° C for 5 min. Thereafter, the temperature was gradually increased from 70 to 100 ° C over 60 min and the temperature was held at 100 ° C for 90 min.

It can be seen from table C that, despite the low modulation index (có ‘), the exchange power was very high and that the fraction of coarse particles (c4) was completely missing.

Example XIII

Example X was repeated, with the following variations: a) temperature of the silicate solution was lowered to 23 ° C; B) the aluminate solution contained 90.8 kg more water

while the silicate solution contained 90.8 kg less water. In other words, the global proportions of the components (NagO, AlgO2, SiOg, HgO) were left unchanged, but a more concentrated silicate solution in which the 20 mol ratio SiOgiHgO was increased to 0.138 (in Example X) was assumed.

the ratio was equal to 0.069)

Table C shows that a satisfactory exchange power and an excellent modulation index were obtained with a fraction of coarse particles (<<* 1) just on the limit of what is still acceptable.

Example XIV

Example X was repeated with the following variations: a) the temperature of the silicate solution was lowered to 25 ° C; B) the aluminate solution contained 103 kg of water more while the silicate solution contained 103 kg of water less, so that the molar ratio SiOgrHgO in the silicate solution increased to 0.159 * The very poor results (Table D) show that a low concentration of silicon dioxide in the starting solution an essential condition for the synthesis of high-quality zeolites.

80 0 0 3 66 13

Example XV

Example XIV was repeated, bringing the temperature of the silicate solution to 65 ° C, causing the viscosity to drop to about 1A from the baseline viscosity (at 25 ° C). Rather than obtaining better results and acceptable results as would be expected (see Table D), an exchange power for calcium was found to be inferior to that obtained in Example XIV and granulometric parameters were obtained which were about as bad as those in the previous example, this proves how critical the dilution of the silicate solution is and excludes that poor results are due to phenomena related only to the viscosity of the solution itself.

Example XVI

Example XV teaches that the dilution of the silicate solution is a critical and necessary factor in the process. This example shows that the dilution is not in itself a "sufficient" factor unless it is accompanied by a sufficiently low SiO 2: Na 2 O ratio. To this end, an aluminate solution was prepared with 276.6 kg of a 35 wt.% Solution of Na 2 O, 71 5 kg of hydrated alumina and an AlgO 2 content of 63 2 wt.% And 610 tb kg of deionized water, were heated to 70 ° C and added to this solution over 15 minutes with stirring 211.2 kg of a silicate solution, temperature 23 ° C, containing 19 * 9 wt. # SiO2 and 5 59 wt.% SiO2, mole ratio SiO2: Na2O = 3 * 5; Proceed as described in Example I and a markedly poor product was obtained containing a very large fraction of coarse particles (ί <= U, see Table D).

Example XVII

In an insulated reactor with a capacity of 70 m, which was equipped with a stirrer and with an external heating (by means of a recirculation pump and a heat exchanger), 12.320 kg of a 35.5 wt. 3,680 kg hydrated alumina, NagQ 2 content 61.3, 35 wt. 1, and 17,120 kg deionized H 2 O; this reaction mixture was heated to 100 ° C until the alumina was dissolved. Then 800 0 3 66 1¾ 11 +, 620 kg of deionized water were added, the temperature dropping to 75 ° C. At that time, 12.21 + 0 kg of an aqueous solution of silicate, temperature 22 ° C, containing 17-16 wt. SiO 2 and 8.61% by weight of NagO, were added over 15 minutes with stirring; the temperature was held at 75 ° C for 1 + 5 min and then gradually increased to 90 ° C over 60 min. The mixture was then kept at 90 ° C for 1h after which it was filtered, washed and dried. The product had the properties listed in Table D.

Example XVIII

Into the reactor described in Example XVII were charged 12,700 kg of a solution of 35 wt.% NagO, 3,610 kg of hydrated alumina, content of AlgO2, 61.3 wt., And 17,760 kg of deionized water, after which the entire mixture at 100 ° C was heated until the alumina was dissolved. Then 11 +, 91 + 0 kg of deionized water were added, causing the temperature to drop to 75 ° C. At that time, 11,500 kg of a silicate solution containing 18.1 + 0% by weight SiOg and 8.70% by weight Na2 O and having a temperature of 23 ° C were added in 15 min. The temperature was held at 75 ° C for 1 + 5 min and then gradually increased to 98 ° C over 20 min. The reaction mixture was then kept at 98 ° C for 30 minutes after which it was filtered and the product was washed and dried. Excellent results have been obtained which are listed in Table E.

25 Example XIX

Example X was repeated using the following variations: a) the temperature of the silicate solution was lowered to 22 ° C; B) the solution of the aluminate contained 150 kg less water, while the silicate solution contained 150 kg more water, so that the degree of dilution of the silicate solution was higher (the mol ratio SiOgjHgO was only 0.038). No satisfactory results have been obtained which are listed in Table E. This shows that not only a limited dilution is detrimental to the synthesis (Examples XIII and XIV) but also an excessive dilution should be avoided; it is therefore recommended to keep the molar ratio SiO4HgO in the silicate solution within the limits indicated by experimental practice, taking into account the other critical parameters, of course.

Example XX

Into the reactor of Example 1 were charged 255 kg of a solution containing 35.5 wt / S Na 2 O, 72.89 kg of hydrated alumina with an Al 2 content of 63.21% by weight and JbQ kg of deionized water. The entire mixture was then heated to 100 ° C until complete dissolution had taken place. The mixture was then cooled to 70 ° C and then further added in 15 min. 148 kg of a solution containing 28.76 wt% SiO2 and 1U v% Na2O corresponding to a molar ratio SiO2: Na2O = 2.1 and which had a temperature of 21 ° C. The other data and results are shown in Table E.

80 0 0 3 66

Table A

Features Ex I Ex Ex II Ex. IV Ex. V

6

SiC> 2: Na2O in the silicate solution 2.2 3.6 2.8 2.0 mixing time (in minutes) 13 '15' 15 '15' ratios ïa20: Al2O3 2.1 + 9 2.1 + 7 2.1 +7 2.1 + 7 in the Na2O: SiO2 2.60 2.60 2.60 2.59 reaction mixture H2O: SiO2 23.9 * 1 23.89 23.89 23.91 exchange power 15 min. Stirring Ca ++ 177 163 173 175 "" "Mg ++ 1 + 5 29.5 28 1 + 5 2 min. Stirring Ca ++ 11 + 5 123 137 1U5» 5 "" "Mg ++ 16 13.5 11+ 21+ granulometry: <2 µm 2, 5¾ 1 # 1.5¾ 3¾ <3 / um 13¾ 1 + ¾ 8.5¾ 21.5¾ <5 / um 68¾ 26¾ 50¾ 89¾ <8 / um 98.5¾ 69¾ 85¾ 98¾ <lOyum 100¾ 83¾ 90¾ 99¾ coarse fraction (oC) 0 17 10 1 modulation (> ^) 85.5 65 76.5 76.5 β> 80 0 0 3 66

Features Ex. VI Ex. VI. Ex. VIII Ex. IX

Table B

17

SiO ^ NagO in the silicate solution 1.7 2.5 2.2 2.2 mixing time (in minutes) 15 '13' 1 * 5 '5' ratios NagOiAlgO ^ 2.1 * 7 2.1 * 9 2.1 * 9 2.1 * 9 in the Na ^ rSiOg 2.60 2.60 2.60 2.60 reaction mixture H ^ OiSiOg 23.90 23.9l * 23.9 ^ 23.9l * exchange power 15 min. Stirring Ca ++ 175 .5 175 166 172.5 "" "Mg ++ 1 * 5.5 1 * 5 1 * 2.5 50 2 min. Stirring Ca ++ 11 + 8.5 11 + 5.5 11 * 0 152" "" Mg ++ 20, 5 20.5 17 22.5 granulometry: <2 / Um 3? 2? 1 # 2.5? <.3 um 28? H +? 9? 17? <5.urn 83? 80? 72? 85? <-8 / Ua 97.5? 97? 98? 97? <10, um 98.5? 98? 99? 98? coarse fraction (<<) 1.5 2 1 2 modulation (^) 69.5 83 89 80 »80 0 0 3 66

Table C

Features Ex. X Ex. XI Ex. XII Ex. XIII

18

SiO ^ ^ Na ^ O in the solution 2.0 2.0 2.0 2.0

SiOgHgO in the solution 0.069 0.069 0.069 0.138 temperature in the

solution 65 ° C 50 ° C 23 ° C 23 ° C

mixing time (in minutes) 15 '15' 15 '15' ratios Iia ^ iAl ^ 2.1 + 2 see see see in Na ^ OiSiOg 2.60 ex. e.g. e.g.

reaction mixture H2Q: SiQ2 23.87 X X X

duration second see

bottom stage 15 '15' 60 'ex. X

alternating power 15 min. stirring Ca ++ 170 175 175.5 172.5 "" "Mg ++ 1 + 1 + 1 + 7 52 1 + 2 2 min. stirring Ca ++ 132.5 137.5 158 129 2" "Mg ++ 3.5 3.5 23 3.5 granulometry: <2 / m 2.5? K% k% Q, 5% <3 µm. 16% 16% 28% 6.5? <5 µm 71.5? 87? 92.5 ? 1 + 1? <L8 / um 96? 97? 99.5? 91 *? <10 / um 98? 98.5? 100? 99? Coarse fraction (> £) 2 1.5 0 1 modulation (ü> ) 80 81 71, 5 87.5 80 0 0 3 66

Features Vb.XIX Vb.XV Vb.XVI Vb.XVII

Table D

19

SiOgiNa ^ O (silicate solution) 2.0 2.0 3.5 2.1

SiO 4 rH 2 O (silicate solution) 0.159 0.159 Q, 080 0.069

temperature (silicate solution) 25 ° C 65 ° C 23 ° C 22 ° C

mixing time (in minutes) 15 '15' 15 '15' ratios NagOïAlgO ^ see see 2.42 2.41 in the Ua20: SiQ2 ex. e.g. 2.60 2.58 reaction mixture H 2 O: SiO 2 X X 23.87 23.90 duration second see see see under step eg. X ex, X ex. X 60 'alternating power 15 min. Stirring Ca ++ 170 168 174.5 175 "" "Mg ++ 21 38 42 51 2 min. Stirring Ca ++ 123.5 125.5 126 156" "" Mg ++ 0 0.5 14 20 granulometry: - C2yum 1 $ 1 $ 1.5 $ 3 $ L 3yum 4 $ 3.5 $ 15 $ 28.5 $ <5 / um 25.5 $ 23.5 $ 74 $ 91.5 $ £ 8yum 68 $ 71.5 $ 94 $ 99.0 $ <10 / um 86 $ 89.5 $ 96 $ 100 $ coarse fraction (^ 4) 14 10.5 4 0 modulation (tü) 64 68 79 70.5 80 0 0 3 56

Features Ex.XVIII Ex.XIX Ex.XX Ex.II

20

Table E

SiOgiNagO (silicate solution) 2.2 2.0 2.1 2.18

SiO4 gO (silicate solution) 0.076 0.038 0.151 0.117

temperature (silicate solution) 23 ° C 22 ° C 21 ° C 10 ° C

mixing time (in minutes) 15 '15' 15 '15' ratios NagOiAlgO ^ 2,. 1 + 9 see 2.1 + 2 2.1 + 1 + in the Na2O: SiO2 2.60 ex. 2.61 2, p1 reaction mixture H 2 O: SiO 2 23.95 X 23.87 21 +, 36 duration second 20 '15' 60 '15' substep alternating power 15 min. Stirring: Ca ++ 176 167 17I + 176 "" "Mg ++ 1+ 6 31 1 + 1 "1 + 3 2" "Ca ++ ll + 2 121 11 + 7.5 1> +1+" "" Mg ++ 11+ 13.5 15 21.5 granulometry: 4 2 ^ um 3% 1 # 3% 1.5% <3 / am lk% 3.5% 11J6 9% <5 / m 10% 31% hl, 5% 11% <8yum 99% 89% 9h% 98% <10 / um 100? 96 .5? 98.5? 99% coarse fraction (cC) 0 3.5 1.5 1 modulation (6j) 85 85.5 83 89 80 0 0 3 66

Claims (7)

1. Process for the preparation of 1 + A zeolites with a high crystallinity and a fine grain size distribution, by first adding an aqueous solution of sodium silicate 5 to an aqueous solution of sodium aluminate containing an excess of sodium hydroxide and preheated to a temperature of 50 to 100 ° C and by crystallization in a second stage at a temperature of JO to 105 ° C, characterized in that the temperature of the silicate solution is at least 20 ° C lower than IQ the temperature of the aluminate solution, the molar ratios SiOgiHgO and SiO ^ NagO in the silicate solution, respectively. lying between 0.030 and 0.150 and between 1.95 and 2.30 and the weight ratio (° T) between the reaction mother liquor and the zeolite thus formed, containing 22% by weight of crystal water, 6.5 to 20, but preferably 8 to 15] is 5. Method according to claim 1, characterized in that the ratio SiOgiHgO is between 0.00 and 0.11 + 0. Method according to claim 1 or 2, characterized in that the silicate solution is added in a time course of 20 at most 15 min, 1 *. Process according to any one of the preceding claims, characterized in that the temperature of the aluminate solution is 70 to 75 ° C and that the temperature of the reaction mixture in the first stage is kept at a value substantially equal to that of the temperature of the aluminate solution. Method according to any one of the preceding claims, characterized in that the second stage of the synthesis is divided into three sub-stages, the temperature in the first sub-stage being maintained substantially equal to the temperature in the first stage, second stage, the temperature is gradually increased from the temperature in the first stage to the temperature of the third stage and the temperature in the third stage is maintained from 95 to 105 ° C, 6. A method according to claim 5, characterized in that the duration of the first sub-stage is 30 to 60 min. But preferably 1 + 0 to 50 min., The duration of the second sub-stage 80 0 0 3 66> · 10 to 8θ but preferably 15 to min. and the duration of the third sub-stage is 10 to 90 but preferably 15 to 60 min. 7-A-Zeolite with a fraction of coarse particles of 50 and with an equivalent magnesium exchanging power of 1 * 5 mg CaO / g or more. Zeolite according to claim 7, characterized in that it has a granulometric modulation index of 85 or greater. 9. A-Zeolite according to claim 7 or 8, characterized in that it has an equivalent magnesium exchanging power of 50 mg CaO / g or more. 10. Methods, substantially as described in the description and / or the examples. 11. Products substantially as described in the description and / or the examples. 80 0 0 3 66